How do you get the 2017 LLN Dash9 Gaming?
It was sold in the League of Legends store. Riot's description in the client reads: “This icon was released in the store for purchase during the 2017 esports season.”
Is the 2017 LLN Dash9 Gaming still available?
Probably not. Riot tied the 2017 LLN Dash9 Gaming to 2017 (store purchase), and it does not normally bring back past event rewards or bundles.
